Journal ArticleDOI
Mechanism Dictates Mechanics: A Molecular Substituent Effect in the Macroscopic Fracture of a Covalent Polymer Network.
Shu Wang,Haley K. Beech,Brandon H. Bowser,Tatiana B. Kouznetsova,Bradley D. Olsen,Michael Rubinstein,Stephen L. Craig +6 more
Reads0
Chats0
TLDR
In this paper, the fracture energy of poly(ethylene glycol) (PEG) gels is controlled by mechanophores embedded within mechanically active network strands, which is a mechanochemical "weak link".Abstract:
The fracture of rubbery polymer networks involves a series of molecular events, beginning with conformational changes along the polymer backbone and culminating with a chain scission reaction. Here, we report covalent polymer gels in which the macroscopic fracture "reaction" is controlled by mechanophores embedded within mechanically active network strands. We synthesized poly(ethylene glycol) (PEG) gels through the end-linking of azide-terminated tetra-arm PEG (Mn = 5 kDa) with bis-alkyne linkers. Networks were formed under identical conditions, except that the bis-alkyne was varied to include either a cis-diaryl (1) or cis-dialkyl (2) linked cyclobutane mechanophore that acts as a mechanochemical "weak link" through a force-coupled cycloreversion. A control network featuring a bis-alkyne without cyclobutane (3) was also synthesized. The networks show the same linear elasticity (G' = 23-24 kPa, 0.1-100 Hz) and equilibrium mass swelling ratios (Q = 10-11 in tetrahydrofuran), but they exhibit tearing energies that span a factor of 8 (3.4 J, 10.6, and 27.1 J·m-2 for networks with 1, 2, and 3, respectively). The difference in fracture energy is well-aligned with the force-coupled scission kinetics of the mechanophores observed in single-molecule force spectroscopy experiments, implicating local resonance stabilization of a diradical transition state in the cycloreversion of 1 as a key determinant of the relative ease with which its network is torn. The connection between macroscopic fracture and a small-molecule reaction mechanism suggests opportunities for molecular understanding and optimization of polymer network behavior.read more
Citations
More filters
Journal ArticleDOI
Molecular Characterization of Polymer Networks.
Scott P. O. Danielsen,Haley K. Beech,Shu Wang,Bassil M. El-Zaatari,Xiaodi Wang,Liel Sapir,Tetsu Ouchi,Zi Wang,Patricia N. Johnson,Yixin Hu,David J. Lundberg,Georgi Stoychev,Stephen L. Craig,Jeremiah A. Johnson,Julia A. Kalow,Bradley D. Olsen,Michael Rubinstein +16 more
TL;DR: A critical overview of the current characterization techniques available to understand the relation between the molecular properties and the resulting performance and behavior of polymer networks, in the absence of added fillers, can be found in this paper.
Journal ArticleDOI
A Mortise-and-Tenon Joint Inspired Mechanically Interlocked Network
Dong Zhao,Zhaoming Zhang,Jun Zhao,Kai Liu,Yuhang Liu,Guangfeng Li,Xinhai Zhang,Ruixue Bai,Xue Yang,Xuzhou Yan +9 more
TL;DR: In this article, a mechanically interlocked network (MIN) inspired by a mortise-and-tenon joint inspired mechanically interlocking network is presented. But the model is based on a rotaxane crosslink.
Journal ArticleDOI
Understanding the Mechanochemistry of Ladder-Type Cyclobutane Mechanophores by Single Molecule Force Spectroscopy.
Matias Horst,Jinghui Yang,Jan Meisner,Tatiana B. Kouznetsova,Todd J. Martínez,Todd J. Martínez,Stephen L. Craig,Yan Xia +7 more
TL;DR: In this paper, a series of ladder-type cyclobutane mechanophores, polymers of which can transform from nonconjugated structures to conjugated structures and change many properties at once, are reported.
Journal ArticleDOI
Single-Event Spectroscopy and Unravelling Kinetics of Covalent Domains Based on Cyclobutane Mechanophores
Brandon H. Bowser,Shu Wang,Tatiana B. Kouznetsova,Haley K. Beech,Haley K. Beech,Bradley D. Olsen,Bradley D. Olsen,Michael Rubinstein,Stephen L. Craig +8 more
TL;DR: In this paper, a covalent synthetic mimics of the mechanical unfolding of noncovalent “stored length” doma... is proposed to serve as a synthetic mimic of the unfolding of polymer contour length.
Journal ArticleDOI
Rational mechanochemical design of Diels-Alder crosslinked biocompatible hydrogels with enhanced properties.
Sophia J. Bailey,Christopher W. Barney,Nairiti Sinha,Sai Venkatesh Pangali,Craig J. Hawker,Matthew E. Helgeson,Megan T. Valentine,Javier Read de Alaniz +7 more
TL;DR: This study illustrates that strategic molecular-level design of DA crosslinks can provide biocompatible materials with improved processing, mechanical durability, lifetime, and utility.
References
More filters
Journal ArticleDOI
A stepwise huisgen cycloaddition process: copper(I)-catalyzed regioselective "ligation" of azides and terminal alkynes.
Journal ArticleDOI
Rupture of rubber. I. Characteristic energy for tearing
R. S. Rivlin,A. G. Thomas +1 more
TL;DR: The resistance to tearing of a rubber vulcanizate is usually determined by loading in a specified manner a test-piece of the vulcanizer of standard shape, in which a notch has been produced, either in the molding process or by cutting the testpiece in a standard fashion.
Journal ArticleDOI
Toughening Elastomers with Sacrificial Bonds and Watching Them Break
Etienne Ducrot,Yulan Chen,Markus Johannes Henricus Bulters,Rint P. Sijbesma,Costantino Creton,Costantino Creton,Costantino Creton +6 more
TL;DR: In this article, a variable proportion of isotropically prestretched chains that can break and dissipate energy before the material fails is introduced to increase the stiffness and toughness of brittle elastomers.
Journal ArticleDOI
The strength of highly elastic materials
G. J. Lake,A. G. Thomas +1 more
Abstract: Under repeated stressing, cracks in a specimen of vulcanized rubber may propagate and lead to failure. It has been found, however, that below a critical severity of strain no propagation occurs in the absence of chemical corrosion. This severity defines a fatigue limit for repeated stressing below which the life can be virtually indefinite. It can be expressed as the energy per unit area required to produce new surface ( T 0 ), and is about 5 x 10 4 erg/cm 2 . In contrast with gross strength properties such as tear and tensile strength, T 0 does not correlate with the viscoelastic behaviour of the material and varies only relatively slightly with chemical structure. It is shown that T 0 can be calculated approximately by considering the energy required to rupture the polymer chains lying across the path of the crack. This energy is calculated from the strengths of the chemical bonds, secondary forces being ignored. Theory and experiment agree within a factor of 2. Reasons why T 0 and the gross strength properties are influenced by different aspects of the structure of the material are discussed.
Journal ArticleDOI
Single molecule force spectroscopy by AFM indicates helical structure of poly(ethylene-glycol) in water
TL;DR: In this article, the resistive force as a function of elongation in different solvents was observed and the molecular response was found to be fully reversible and thus in thermodynamic equilibrium.